Lift mechanism

ABSTRACT

A scissors-type lift mechanism employs a reciprocating cam wedge adapted to engage cam follower rollers mounted on collapsed, transversely arranged scissor arms movable in the vertical plane. Movement of the cam in one direction forces the arms apart into a lifting movement as the rollers follow engaged cam surfaces. Movement of the cam in an opposite direction allows the scissor arms to collapse. In a modified construction, slotted toggle links pivotally connected to the cam engage pins on the scissor arms to effect an additional arm-spreading or lifting action after an initial spreading action effected by the cam.

United States Patent [191 Butler [451 Aug. 26, 1975 1 1 LIFT MECHANISM[75] Inventor: Louis L. Butler, Baton Rouge, La.

[73] Assignee: Bear Manufacturing Corporation, Rock Island, 11].

221 Filed: Mar. 15', 1972 211 Appl. No.: 234,839

[52] US. Cl. 187/8.7l; 187/18; 254/104; 254/122 [51] Int. Cl B66f 7/08[58] Field of Search l87/8.7l, 18, 8.72; 254/122, 126, 104; 74/89, 99,99 A [56] References Cited UNlTED STATES PATENTS 1,991,255 2/1935 Martin254/126 3,350,065 10/1967 Mankcy 187/18 X 3,556,481 1/1971 Mueller eta1. 254/122 Primary Examiner-Evon C. Blunk Assistant Examiner.lames L.Rowland Attorney, Agent, or Firm-Roy E. Petherbridge; Robert L.Lindgren; Edward D. Gilhooly 5 7] ABSTRACT A scissors-type liftmechanism employs a reciprocating cam wedge adapted to engage camfollower rollers mounted on collapsed, transversely arranged scissorarms movable in the vertical plane. Movement of the cam in one directionforces the arms apart into a lifting movement as the rollers followengaged cam surfaces. Movement of the cam in an opposite directionallows the scissor arms to collapse.

In a modified construction, slotted toggle links pivotally connected tothe cam engage pins on the scissor arms to effect an additionalarm-spreading or lifting action after an initial spreading actioneffected by the cam.

10 Claims, 6 Drawing Figures LIFI MECHANISM This invention relates to ascissors-type lift mechanism particularly adapted for use in theservicing of vehicles as by lifting automobiles or the like verticaldistances.

The increasing costs pertaining to the purchase and maintenance ofautomobiles have impressed upon the auto-owning public in general thedesirability of maintaining automobiles in peak operating condition. Oneof the more prominent areas in which constant vigilance is exercised bythe typical auto owner is that of wheel alignment. Improper alignmentresults in rapid tire wear which necessitates early and costly tirereplacement, and in the aggravated instances causes tread wear to theextent that the tires provide inadequate and unsafe traction.

Auto-lifting devices which provide a vertical lifting actionfacilitating a variety of servicing functions such as wheel alignmentservice, transmission service, exhaust system service, etc. are in everincreasing demand.

Many prior art automotive lifting devices comprising spaced runways aresupported by a central supporting cylinder or include other apparatusbetween the runways and/or require subfloor installations. Such devicesare costly to install, consume a maximum amount of valuable work area,and prevent access to the vehicle underside in the central area.

It is an object of this invention to provide an improved lifting deviceemploying a simple scissor arm action and which may be used to raiseautomotive vehicles and the like vertical distances to provide accessto, and thus facilitate servicing of, the vehicle wheels and underside.

It is another object of this invention to provide a novel lift mechanismwhich occupies a bare minimum of space in the collapsed and extendedpositions allowing maximum utilization to be made of the work area whereinstalled. Yet the novel lift disclosed hereinafter allows ready accessto substantially the entire vehicle undersurface when elevated.

It is a further object of this invention to provide a lift mechanismwhich is of novel design providing optimum mechanical efficiency in theelements employed so as to obtain maximum utilization of the powersource employed. Said power source is thus maintained at a minimum sizewith resulting minimum purchase and maintenance costs.

The above and other objects of this invention will become more apparentfrom the following detailed description when read in the light of thedrawing and the appended claims.

In one embodiment of this invention twin vehicle supporting runwaysdisposed in spaced relation are supported atop two scissors-type liftmechanisms. The scissor arms of each lift are pivotally connected andoperable in the vertical plane. The arms move from a lower position inwhich they are substantially horizontal in side-by-side relation to anupper extended position defining the maximum vertical lift of the runwaysupported by the upper ends of the scissor arms.

Cam follower rollers are mounted in superposed relation on the armsadjacent the pivot'point of the transversely arranged scissor arms ofeach lift. A horizontally movable wedge cam spreads the cam followersapart forcing the arms to move about their pivot point whilesimultaneously causing the arm upper ends and runway supported thereonto rise in the vertical plane.

Slotted toggle links pivotally mounted on the cams afford additionalarm-spreading action and runway lift in a modified constructionhereinafter explained in greater detail.

FIG. 1 is a perspective view of a vehicle lift mechanism made inaccordance with this invention in the elevated or lifting position;

FIG. 2 is a fragmentary sectional view illustrating lifting elements ofthe device of FIG. 1 in the collapsed condition housed within a runwaymember;

FIG. '3 is a fragmentary side view partly broken away illustrating thewedge cam of the provided lift in the extended position providingmaximum lift;

FIG. 4 is a view similar to FIG. 2 illustrating a modified liftconstruction employing slotted toggle links;

FIG. 5 is a fragmentary side elevational view of the elements of FIG. 4disposed in an initial stage of the lifting action, effected by means ofthe illustrated cam wedge; and

FIG. 6 is a view similar to FIG. 5 illustrating the position at whichthe toggle links of the illustrated lift elements complete theirspreading action on the scissor arms.

Referring now to FIG. 1 a vehicle rack 10 is illustrated comprisingspaced wheel supporting runways or tracks 12 each of which is supportedby a scissors-type lift mechanism 14. The tracks may employ usualinclined ends 16 to facilitate driving of the vehicle onto the tracksand fixed stops 18 at the opposed track ends as well as movable stops 20which elevate into the stop positions illustrated with the elevation ofthe rack off i a supporting floor surface.

In accordance with this invention a simple, unique cam-cam followerarrangement seen most clearly in FIG. 3 is employed to impart aspreading action to arms 22 and 24 of each twin lift mechanism 14. Eacharm 22 and 24 may assume the form of a U-shaped channel having opposedside flanges to facilitate the mounting of various roller membersemployed. The channels may be cut away in appropriate areas to allow thedesired scissors action. Alternatively each arm 22 and 24 may comprisespaced strips or bars maintained in desired parallel relation byconnecting transverse straps.

As noted in FIG. 3, arms 22 and 24 are transversely arranged andpivotally connected at their centers by pin 26 which also serves as amount for pivotally movable hydraulic cylinder 28. Piston arm 30 isreciprocally movable in cylinder 28 and has cam wedge 32 disposed at theend thereof. Wedge 32 serves to spread apart scissor arms 22 and 24 aspiston arm 30 extends from the cylinder by engaging vertically alignedrollers 34 and 36 rotatably mounted on scissor arms 22 and 24,respectively. Aligned rollers 34 and 36 are preferably disposed as closeto the pivot pin 26 as possible to afford the maximum spreading actionduring wedge movement with a resulting maximum lifting action.

As is also seen in FIG. 3, the lower end of arm 22 of each mechanism 14has a roller support 38 enabling the arm to travel over floor F in thecourse of lift elevation or retraction. Roller 38 may engage a travelplate such as plate 40 illustrated in FIG. 1. The lower end of each arm24 may be pivotally mounted in an anchor plate such as plate 42 ofFIG. 1. Roller 38 may be confined in a track (not illustrated) whichprevents the possibility of upward movement from the supporting floor orplate.

As the scissor arms of each elevating mechanism 14 spread, rollers 44(see FIG. 2) mounted on the upper ends of arms 24 rotatably engageundersurface portions of runways 12. The rollers 44 are confined inguide tracks (not illustrated) to prevent disengagement from the engagedrunways. The upper ends of scissor arms 22 may be pivotally anchored asby pins 45 seen in FIG. 1 to depending flange portions of runways 12.FIG. 3 illustrates the cam wedge 32 in its maximum extended positionrelative to cylinder 28 and accordingly arms 22 and 24 are shown intheir maximum spreadapart position.

Toggle links 46 and 48 illustrated in FIGS. 4 through 6 enableadditional spreading action to be imparted to arms 22a and 24a of eachtwin lift mechanism after the cam wedge has initially spread the scissorarms. Each link 46 and 48 is pivotally mounted at one inner end on pin49 of cam 32a and is slotted at 50 for lost-motion passage of pins 52 onwhich rollers 34a and 36a are mounted. The slots 50 enable the arms 22aand 24a to assume the spread position illustrated in FIG. 5 before thelinks become functional by engaging pins 52 at the inner ends of theslots 50. In the position illustrated in FIG. 5 the thrust exerted onthe pin 49 by the piston arm 30 will result in significant verticalforce vectors being transmitted to the pins 52 and arms 22a and 24a tospread the pins vertically. Such vectors are minimal with the arms inthe fully collapsed position of FIG. 4.

FIG. 6 is illustrative of the arms 22a and 24a of a lift mechanism inthe course of positively being spread apart by toggle links 46 and 48,and near the maximum spread or lift position.

The links 46 and 48 are thus seen to provide an in creased verticaldisplacement to the supported runways 12 while in no way increasing thedepth of the disclosed lifting rack 10 in the collapsed condition; seeFIGS. 2 and 4.

The lifting apparatus in each embodiment occupies a minimum verticalspace or vertical depth. This permits storage of the lift mechanismwithin the depth of a shallow track 12 on a flat floor surface.Moreover, the lifting action is effected by a simple reciprocatory drivemotion of the piston rod 30 in each instance.

The pivotal cam and cylinder assembly is pivoted to remain substantiallyhorizontal, since the cam portion thereof is locked between the rollers34 and 36 regardless of the vertical interval between the rollers. Suchhorizontal disposition is present in both illustrated embodiments. Also,since the transversely arranged arms of each scissors lift are pivotallyconnected at their centers, the supported runways remain horizontal asthey rise vertically, with no lateral shifting.

It should be noted that an additional benefit resulting from use of thedisclosed apparatus is the complete open area between the runways whichmay be occupied by service personnel and/or equipment when the rack ofthis invention is in the elevated position.

It is apparent that the operating controls for the described liftmechanism are simple in nature and as a result have low initial cost andare inexpensive to maintain. Hydraulic fluid may be supplied to thecylinder 28 of each lift 14 to simultaneously raise the runways and maybe similarly simultaneously released from such cylinders to retract thecam wedges 32 or 32a when it is desired to lower the runways. Auxiliaryfeatures known in the art may be employed with the devices abovedescribed such as safety supports which wedge between the runways andfloor to guard against hydraulic failure.

It will be apparent to those skilled in the art that other modificationsand embodiments of the specific apparatus disclosed herein may be madewithout departing from the spirit and scope of the invention. Particularconstruction and fabrication details of one embodiment are disclosedonly by way of example, and the various components may be fabricated andassembled in other configurations. For instance, a single lift mechanismemploying teachings of the invention and of appropriate dimensions maybe utilized as an independent jack for other purposes.

It will be seen that improvements have been provided which meet theaforestated objects.

While a particular embodiment of this invention is shown and describedherein, it will be understood, of course, that the invention is notlimited thereto, since many modifications may be made by those skilledin the art, particularly in light of the teachings herein. It iscontemplated, therefore, by the appended claims to cover any suchmodifications as fall within the true spirit and scope of thisinvention.

What is claimed is:

1. In a vehicle lifting rack the combination comprising a vehiclesupporting runway, at collapsible scissors type lifting mechanismsupportably engaging undersurface portions of said runway, saidmechanism comprising transversely arranged, pivotally connected scissorarms movable in the vertical plane and assuming a sub stantiallyhorizontal side by side relationship when in the collapsed condition,cam follower means disposed on each of said scissor arms whereby eacharm follower means is arranged in vertically aligned adjacentrelationship with every other cam follower means when said scissor armsare in the collapsed condition, cam means pivotally supported at thepivotal connection of said arms and movable substantially horizontallybetween said cam follower means, said cam means being adapted to forcesaid cam follower means apart and thereby force said scissor arms tomove about their pivotal connection so as to raise their upper ends; theupper ends of said scissor arms supportably engaging said runway.

2. The lifting rack of claim 1 in which said cam followers are rollersmounted on pins anchored in each of said scissor arms; said rollersbeing disposed adjacent the pivotal connection between said scissorarms.

3. The lifting rack of claim 2 in which said cam means comprises a wedgemounted on the end of a reciprocally movable piston rod extending from acylinder, said cylinder being supportably mounted at the pivotalconnection between said scissor arms.

4. The lifting rack of claim 2 in combination with slotted toggle linkspivotally mounted on said cam means and having the slotted portionsthereof slidably engageable with said pins while said cam means engagessaid cam followers; said slots being of such length that said cam meansdisengage from contact with said cam followers when said pins traversethe length of said slots whereafter cam movement forces said scissorarms to move about said pivotal connection by means of said toggle linksas said toggle links pivot about said cam means.

5. An automotive lift rack comprising spaced lifting racks as describedin claim 4 in combination with motive means for simultaneously raisingand collapsing the scissor arms of each of said lifting racks.

6. The rack of claim 1 in which said cam means has a pointed endmaintained between said cam follower means; in which movement of saidscissor arms in the vertical plane causes vertical movement of saidpivotal connection and corresponding pivotal movement of said cam meansrelative thereto; and in which said cam follower means are in verticalalignment and said cam means is disposed at substantially right anglesthereto so as to be always substantially horizontal.

7. In a scissors type lift mechanism for imparting a vertical lift to asupported surface, the combination comprising transversely arrangedscissor arms pivotally connected at their centers, having cam followerrollers mounted thereon which assume an adjacent relationship when saidscissor arms are in a collapsed position, said rollers being in verticalalignment and disposed adjacent the pivot point of said arms when saidscissor arms are in the collapsed condition, power driven cam meanssupported adjacent said cam followers adapted to spread said camfollowers apart and simultaneously force said scissor arms to spreadapart about their pivot point, said cam means having inclined surfacesadapted to move substantially horizontally to so force said rollers intospaced relation, and said scissor arms and the supported surface beingso related that spreading action of the scissor arms imparts verticalmovement to the supported surface.

8. The lift mechanism of claim 7 in combination with slotted togglelinks pivotally mounted on said cam means and slidably engaging pins onwhich said rollers are mounted during said cam-roller engagement bymeans of said slots; said links being adapted to force said scissor armsfurther apart after said wedge has initially spread apart said scissorarms.

9. The lift mechanism of claim 7 wherein said power means includes ahydraulic cylinder supportably mounted at the pivot connection betweensaid scissor arms, a reciprocally movable piston rod extending from saidcylinder toward said cam followers, and said cam means being mounted onsaid piston rod and normally disposed between said pivot connection andsaid cam followers for engaging and forcibly spreading said followersupon outward movement of said cam means relative to said pivotconnection.

10. An automative lift rack comprising a pair of spaced generallyparallel lift mechanisms each as described in claim 7; said power drivencam means of each of said lift mechanisms including a hydraulic cylinderand reciprocable piston rod unit disposed beneath the respectivesupporting surface, and each having a cam member mounted on said pistonrod; the space between said mechanisms being unobstructed; and hydraulicmotive means for simultaneously actuating said cylinders forsimultaneously raising and collapsing the scissor arms of saidmechanisms.

1. In a vehicle lifting rack the combination comprising a vehiclesupporting runway, a collapsible scissors type lifting mechanismsupportably engaging undersurface portions of said runway, saidmechanism comprising transversely arranged, pivotally connected scissorarms movable in the vertical plane and assuming a substantiallyhorizontal side by side relationship when in the collapsed condition,cam follower means disposed on each of said scissor arms whereby eacharm follower means is arranged in vertically aligned adjacentrelationship with every other cam follower means when said scissor armsare in the collapsed condition, cam means pivotally supported at thepivotal connection of said arms and movable substantially horizontallybetween said cam follower means, said cam means being adapted to forcesaid cam follower means apart and thereby force said scissor arms tomove about their pivotal connection so as to raise their upper ends; theupper ends of said scissor arms supportably engaging said runway.
 2. Thelifting rack of claim 1 in which said cam followers are rollers mountedon pins anchored in each of said scissor arms; said rollers beingdisposed adjacent the pivotal connection between said scissor arms. 3.The lifting rack of claim 2 in which said cam means comprises a wedgemounted on the end of a reciprocally movable piston rod extending from acylinder, said cylinder being supportably mounted at the pivotalconnection between said scissor arms.
 4. The lifting rack of claim 2 incombination with slotted toggle links pivotally mounted on said cammeans and having the slotted portions thereof slidably engageable withsaid pins while said cam means engages said cam followers; said slotsbeing of such length that said cam means disengage from contact withsaid cam followers when said pins traverse the length of said slotswhereafter cam movement forces said scissor arms to move about saidpivotal connection by means of said toggle links as said toggle linkspivot about said cam means.
 5. An automotive lift rack comprising spacedlifting racks as described in claim 4 in combination with motive meansfor simultaneously raising and collapsing the scissor arms of each ofsaid lifting racks.
 6. The rack of claim 1 in which said cam means has apointed end maintained between said cam follower means; in whichmovement of said scissor arms in the vertical plane causes verticalmovement of said pivotal connection and corresponding pivotal movementof said cam means relative thereto; and in which said cam follower meansare in vertical alignment and said cam means is disposed atsubstantially right angles thereto so as to be always substantiallyhorizontal.
 7. In a scissors type lift mechanism for imparting avertical lift to a supported surface, the combination comprisingtransversely arranged scissor arms pivotally connected at their centers,having cam follower rollers mounted thereon which assume an adjacentrelationship when said scissor arms are in a collapsed position, saidrollers being in vertical alignment and disposed adjacent the pivotpoint of said arms when said scissor arms are in the collapsedcondition, power driven cam means supported adjacent said cam followersadapted to spread said cam followers apart and simultaneously force saidscissor arms to spread aparT about their pivot point, said cam meanshaving inclined surfaces adapted to move substantially horizontally toso force said rollers into spaced relation, and said scissor arms andthe supported surface being so related that spreading action of thescissor arms imparts vertical movement to the supported surface.
 8. Thelift mechanism of claim 7 in combination with slotted toggle linkspivotally mounted on said cam means and slidably engaging pins on whichsaid rollers are mounted during said cam-roller engagement by means ofsaid slots; said links being adapted to force said scissor arms furtherapart after said wedge has initially spread apart said scissor arms. 9.The lift mechanism of claim 7 wherein said power means includes ahydraulic cylinder supportably mounted at the pivot connection betweensaid scissor arms, a reciprocally movable piston rod extending from saidcylinder toward said cam followers, and said cam means being mounted onsaid piston rod and normally disposed between said pivot connection andsaid cam followers for engaging and forcibly spreading said followersupon outward movement of said cam means relative to said pivotconnection.
 10. An automative lift rack comprising a pair of spacedgenerally parallel lift mechanisms each as described in claim 7; saidpower driven cam means of each of said lift mechanisms including ahydraulic cylinder and reciprocable piston rod unit disposed beneath therespective supporting surface, and each having a cam member mounted onsaid piston rod; the space between said mechanisms being unobstructed;and hydraulic motive means for simultaneously actuating said cylindersfor simultaneously raising and collapsing the scissor arms of saidmechanisms.